Telefunken ELA M 250, 251
|Polar pattern||Variable pattern|
|First decade of production||1950s|
The Telefunken Models ELA M 250, 251
multi-directional condenser microphones
The following photographs and schematics are provided through the courtesy of John Warshaw.
Download the ELA M 250 schematic
Mr. Warshaw writes:
The Telefunken ELA M 250/251 was made for Telefunken by AKG after Neumann discontinued its OEM production of the Telefunken U 47. Of course Neumann still made the U 47 for many years. Telefunken needed a quality condenser, and AKG stepped in.
The differences between the C 12 and the ELA M 250 are small but important. The C 12 is remotely controlled for pattern by polarizing the rear diaphragm with a separate variable voltage from the power supply, while the ELA M 250/251 has switches in the capsule assembly that change its polarization pattern. The 250 has two patterns, Omni and Cardioid. The 251 included these patterns and also the figure eight.
The second difference is in the circuit. The C 12 and ELA M 250 circuits are similar but not identical. They both use the CK 12 capsule, T/14 transformer and either the 6072A tube (US version) or the AC701 (Europe), but the grid coupling, cathode bias and capsule polarization are different.
Third, the body style of the C 12 and ELA M 250 are not the same. Most important, the head grilles are different, so acoustics are also different.
The photo of the black mic is not an AKG model but was made by an east German company by the name of Thiele, a rather unknown brand from the forties and fifties. I bought this on ebay five years ago and rewired it in the spirit of the ELA M 250. It works great and I have used it on the KPIG live radio shows on Sunday mornings with Sleepy John.